Welcome dear students! Today we are going to learn about Living Creatures: Exploring their Characteristics from Class 6 Science. Let us begin with a little story. Avadhi and Aayush go for a morning walk with their parents. Avadhi notices some shells and tries to pick them up. Her mother advises her not to do so and explains that the shell could be home to a living snail and is actually a part of its body. Avadhi and Aayush wonder how a shell that is not even moving could have a living being inside! Later that day in school, they share this incident with their friends and approach their teacher. The teacher initiates a class discussion on living and non-living things.
Now let us try Activity ten point one, titled Let us record. We are surrounded by numerous things. Just look around your classroom and you may find many examples, like the pencil you are holding, the book you are reading, or a pigeon near the window. We will list them and identify each as living or non-living. For a pencil, we guess it is non-living. For a book, non-living. For a pigeon, living. For a car, non-living. For a plant, living. We will fill in the reasons and correct answers as we learn.
[CHECKPOINT]
Let us move to section ten point one: What Sets the Living Apart from the Non-living? Look at our list. Why is a pencil non-living but a pigeon living? What differences do you see? You may have identified movement as one similarity among living beings. But you have also seen cars moving. Does it mean a car is living? No. List the tasks that you can do but a car cannot. You are a wonderful example of a living being. Whenever you attempt to group things, compare them with yourself. Which characteristics help you differentiate yourself from a car? For instance, a car does not grow. Can we consider movement as a characteristic to differentiate between living and non-living? List five things around you that can move on their own. Do you think all five are living just because they move? However, unlike animals, plants do not move from one place to another. Do you consider them living? Yes. Even though plants do not move from place to place, they show certain movements. Opening of flowers is one example. Another example is seen in insectivorous plants, which depend on insects for nutrition. Drosera is one example. Drosera features saucer-shaped leaves having many hair-like projections of unequal length with sticky ends. Whenever an insect enters the saucer, hairs move inward and trap the insect with their sticky ends. Climbers also wind themselves around objects placed close to them. So plants do show movements.
[CHECKPOINT]
Compare yourself with a childhood picture. Can you wear a dress from four years ago? No, because you have become larger. This is due to growth in your body. Plants and other living beings also grow. Can we consider growth a characteristic of living beings? Yes. Living beings need food, which is nutrition, for growth and development. List five living beings that require food to grow. Now, think of a process without which we cannot live. Count your breaths per minute after a normal walk, after a run, and after dance steps. Record and observe. Do you notice differences? Do you notice breathing in dogs, cats, cows, and buffaloes? Notice their abdomen movement at rest. In breathing, air moves from outside to inside when we inhale, and from inside to outside when we exhale. Breathing is part of a process called respiration. Do plants respire? Yes. There are tiny pores called stomata on leaf surfaces. These pores help plants take air in and out. All living beings respire.
[CHECKPOINT]
Have you noticed white patches on shirts around armpits in summer? These are sweat. Sweat consists of water and salts removed as waste. Removal of waste products from the body is called excretion. Urine is also an excretion product in animals. Do you know that plants also excrete? You may notice plants excrete excess water and minerals in the form of small droplets on leaves, like on grasses and roses. All living beings excrete. Let us look at another characteristic. What is your reaction if you step on a thorn or touch a hot cup of tea? Stepping on a thorn and touching a hot object are stimuli. Any thing or any event that prompts living beings to respond is called a stimulus. List three stimuli and your instant response. Do plants respond to stimuli? Yes. Touch-me-not plants fold leaves when touched. Some plants fold leaves after sunset. Leaves of amla trees facing each other come together. All living beings respond to stimuli. Have you seen young ones of cats or dogs? List young ones of five animals. Have you seen young ones of non-living things like a pencil or chair? No. All living beings reproduce. Reproduction is the process of producing new ones of one's own kind. It is necessary for continuity of life. When a living being cannot exhibit these characteristics despite available resources like food, air, and water, it is said to be dead. All living beings show movement, need food, grow, respire, reproduce, excrete, respond to stimuli, and eventually die. Absence of any feature indicates non-living things.
[CHECKPOINT]
Now complete Table ten point one columns four and five. A pencil is non-living because it does not grow, eat, or reproduce. A book is non-living for the same reasons. A pigeon is living because it shows all characteristics. A car is non-living because it needs fuel, not food, and does not grow or reproduce. A plant is living because it grows, respires, excretes, and reproduces. In which category would you place a seed? Living or non-living? Why? Let us explore seed germination. Section ten point two covers essential conditions for germination. Let us perform Activity ten point two, titled Let us experiment. Take four identical pots filled with garden soil. Sow four bean seeds in each pot. Keep them for fifteen days. Pot A gets no water, placed in direct sunlight. Pot B gets excess water, placed in direct sunlight. Pot C gets moist soil, kept in dark. Pot D gets moist soil, kept in direct sunlight. When a seed turns into a sprout, it is said to have germinated.
[CHECKPOINT]
Now, let us carefully fill Table ten point two, which records the effect of certain conditions on seed germination. This table tracks each pot's availability of air, sunlight, and water, along with predictions and observations. For Pot A, kept in direct sunlight without water, air is available, sunlight is available, but water is absent. My prediction is no germination. The observation confirms no germination, because water is essential. For Pot B, in direct sunlight with excess water, air is blocked by water, sunlight is available, and water is present. Prediction: no germination. Observation: no germination, because excess water deprives seeds of air. For Pot C, in complete dark with moist soil, air is available, sunlight is absent, and water is present. Prediction: germination. Observation: germination occurs, because light is not essential for bean seed germination. For Pot D, in direct sunlight with moist soil, air, sunlight, and water are all available. Prediction: germination. Observation: germination occurs, as all essential conditions are met.
[CHECKPOINT]
Seeds require water and air for germination. Water softens the seed coat and helps the embryo develop. Seeds use air in soil spaces. Spaces also help roots grow. Light is not essential for bean germination, but needed later for seedling growth. However, some seeds of flowering plants, like Coleus and Petunia, require light to germinate. Covering these seeds with soil inhibits their sprouting. On the other hand, seeds of flowering plants, like Calendula and Zinnia, need darkness to germinate. These seeds should be covered with sufficient soil. Here is a special Do you know box for you. In the Chapter Mindful Eating: A Path to a Healthy Body, you have learnt that human beings need a balanced diet for good health and proper growth. Similarly, plants too need favourable conditions and nutrients for their proper growth and development. What other conditions do you think would affect seed germination?
Section ten point three covers growth and movement in plants. How do plants respond to sunlight? Let us design Activity ten point three. Take bean or gram seeds, germinate on moist cloth until they have a small root and shoot. Take three glass beakers labeled A, B, and C. Attach thick blotting paper to three glass plates using soft cotton thread. Fix one seedling on each plate. Place the plate upright in beaker A. In beaker B, arrange the plate so the shoot points down and the root points up. In beaker C, place the plate upright. Pour water so seedlings stay above water but the blotting paper soaks it. Place beakers A and B in sunlight from all directions. Place beaker C in a cardboard box with light from one direction through a small hole.
[CHECKPOINT]
Now, let us record our findings in Table ten point three. This table compares the direction of sunlight, plant orientation, and the resulting growth of roots and shoots. For Beaker A, sunlight comes from all directions, and the plant is upright. For the shoot, I predict it will grow upwards, and the observation confirms it grows upwards. For the root, I predict it will grow downwards, and it does. For Beaker B, sunlight comes from all directions, but the plant is inverted. For the shoot, I predict it will bend and grow upwards, which is observed. For the root, I predict it will bend and grow downwards, which is also observed. For Beaker C, sunlight comes from only one direction, and the plant is upright. The shoot is predicted to grow towards the light, and it does. The root is predicted to grow downwards, and it continues to grow downwards. Shoots grow upward toward sunlight, roots grow downward. Know a scientist: Jagadish Chandra Bose, an Indian scientist, built a machine called a crescograph to record plant responses to stimuli like light, heat, electricity, and gravity. He measured plant growth speed and showed plants sense and respond to stimuli.
[CHECKPOINT]
Section ten point four covers the plant life cycle. Perform Activity ten point four, titled Let us explore. Plant a bean seed, provide suitable conditions, observe for three months. Record your findings in Table ten point four. This table has three columns: Date, Observations, and Sketches. In the first row, under Observations, you will write Seeds are sown. As days pass, you must carefully record answers to specific questions: How long does it take for any change to occur? After how many days does the first flower appear? After some parts of the flower have dried, can you see any further growth? Which structure do the remaining parts of the flower develop into? Can you notice a pod or a fruit with seeds develop from a flower? What happens to the plant after the fruits containing seeds are formed? Make sketches of these changes in the third column. The entire process from a seed to a plant, and then, to the next generation of seeds is called the life cycle of a plant. When a plant stops growing and life activities end despite conditions, it is dead.
Section ten point five covers animal life cycles. Ten point five point one: mosquito life cycle. Female mosquitoes suck blood and transmit malaria, dengue, and chikungunya. Prevent breeding by stopping stagnant water. Conduct a safety audit for stagnant water in coolers, pots, and containers. You may find larvae and pupae. Larvae and pupae come to the water surface for air. Kerosene oil forms a layer blocking air, killing them.
[CHECKPOINT]
Activity ten point five: Let us analyse. Solve a puzzle. Which stage comes after egg? Follow the design created by Avadhi. Step one: I have a water container with mosquito larvae and pupae. Step two: I will separate four to five larvae and pupae into two separate containers with the same water. Step three: I will observe them every day until I see them changing to the next stage. Step four: If the larvae change into pupae, it would mean that the larval stage comes before the pupal stage or vice versa. Step five: I will keep watching both containers to see in which one a mosquito appears first. These observations will help us learn the correct sequence of growth. Without separating them, you can also observe which stage transforms first. Mosquitoes pass through four stages: egg, larva, pupa, adult. Adult rests on water then flies. Survives ten to fifteen days. Significant changes in shape and structure occur. Here is another important Do you know box. The silk moth also passes through four life stages, egg, larva, pupa and adult. Eggs hatch into larvae, which then grow in size. Larvae secrete thread-like material which they wrap around themselves, before changing to pupae. These are the fibres that are used to make silk fabric. In India, the Khadi and Village Industries Commission, known as KVIC, has set up several centres for silk production.
Ten point five point two: frog life cycle. Activity ten point six: Let us analyse. Visit a shallow pond during rain with a facilitator. Observe white jelly-like substance on water edge. This is spawn, a cluster of frog eggs. Record the changes in different life stages in Table ten point five. This table has columns labeled A through F, corresponding to the stages shown in the figure. You will fill in the changes in appearance and body shape for each stage. For example, the table gives a clue for one stage: It is similar to C but it has two legs. Use this to track how the egg becomes an embryo, then a tadpole with a tail, a tadpole with legs, a froglet, and finally an adult frog.
[CHECKPOINT]
After studying the stages, please discuss in class along the following points: How are these eggs of a frog different from the other eggs that you may have seen? Which stage has the shortest duration? Is there a change in the habitat during the various stages in the life cycle of a frog? And how do the special features support that stage? You will notice that tadpoles develop legs but still have tails. Tails help them swim in water. Tadpoles grow gradually and start looking like little frogs called froglets. They still live in water but begin to spend some time on land. They continue to grow and lose their tails completely. Their legs become strong to help them jump and land. They become fully developed adult frogs who live both in water and on land.
Summary: Objects are living or non-living. Living beings move, eat, grow, breathe, excrete, respond to stimuli, reproduce, and die. Germination needs water, air, and suitable light or dark. Roots grow down, shoots grow up. Plant life cycle starts with germination, grows, flowers, produces seeds. Animal life cycle starts with newborn, grows to adult, then dies. Reproduction maintains continuity. Mosquito stages: egg, larva, pupa, adult. Frog stages: eggs, tadpoles, froglets, adults. Significant changes occur in shape, structure, and habitat.
[CHECKPOINT]
Let us review the Keywords for this chapter. Please familiarize yourself with these terms: Breathing, Death, Excretion, Froglet, Germination, Growth, Larva, Life cycle, Living, Movement, Non-living, Nutrition, Pupa, Reproduction, Respiration, Response, Stimulus, and Tadpole. The verbs linked to your learning process are: Conclude, Create, Design, Experiment, Explore, Identify, Observation, and Prediction.
Now let us enhance our learning. Question one: List similarities and differences in life cycles of plants and animals. Similarities: Both start from a reproductive unit, grow, mature, reproduce, and eventually die. Both require suitable conditions. Differences: Plants remain fixed, animals move. Plants produce seeds, animals give birth or lay eggs. Animal life cycles often involve metamorphosis. Question two: Study the data table. The table has columns for Serial number, Does it grow, Does it respire, Example, and Remarks. Row one: Does not grow, does not respire. Find an example and add remarks. Row two: Does not grow, but respires. Find an example and add remarks. Row three: Grows, does not respire. Find an example and add remarks. Row four: Grows and respires. Find an example and add remarks. If an example is impossible for any condition, explain why.
[CHECKPOINT]
Question three: How to use germination conditions for grain storage? Store grains in dry, airtight, cool containers. Removing moisture and air prevents germination and spoilage. Question four: Advantage of a tail in tadpole stage? Helps swim efficiently, escape predators, and find food in water. Question five: Charan says a wooden log is non-living as it cannot move. Charu says it is living because it comes from trees. Give arguments. Charan is correct. A wooden log is non-living. It is cut dead tissue. It does not grow, respire, excrete, respond, or reproduce. Question six: Similarities and differences in mosquito and frog life cycles. Similarities: Both begin with eggs in water, undergo metamorphosis, have aquatic early stages. Differences: Mosquitoes have four distinct stages including a pupa. Frogs have egg, embryo, tadpole, froglet, adult. Mosquito larvae breathe air at surface, frog tadpoles use gills.
Question seven refers to Figure ten point nine. This figure clearly shows a flower pot kept horizontally along the ground, rather than standing upright. Draw what you expect to see in the shoot and root after one week, and write your reasons. You will see the shoot bend upward toward sunlight and the root bend downward into the soil due to phototropism and geotropism. Question eight refers to Figure ten point ten. This figure shows an experimental set-up where a potted plant is placed inside a cardboard box that has only one small circular hole on its side, allowing sunlight to enter from just that single direction. What do you think Tara and Vijay want to find out? They want to see how plants respond to directional light. They will know if they are correct when the shoot bends and grows toward the hole. Question nine asks you to design an experiment to check if temperature affects seed germination. Take three identical pots with moist soil. Sow five bean seeds in each. Place one in refrigerator, one at room temperature, one near heater. Keep water and air same. Observe for ten days. Compare germination rates.
[CHECKPOINT]
Learning further: Make a field trip to a local garden. Interact with a gardener to learn about conditions and time required for plant growth. Explore if we can grow plants without germinating seeds, like through cuttings or tubers. Observe life cycles of five plants at home or school. Create a picture book with stages and durations. Observe butterfly or moth life cycles and compare with mosquitoes. Explore how environment affects insect life cycles. Let us create: Add more lines to the incomplete poem about frogs. Include different stages of frog development. You may also draw and paint each stage as it appears in your poem. The poem begins: In shaded and grassy bogs, there lived a group of frogs. They happily sang from dusk to dawn, in double bass going on and on. One day sitting beside a reed, female frogs think it's time to breed. Continue with the stages of spawn, tadpole, froglet, and adult frog in your own creative words.
Thank you for listening! Keep revising and practicing. Goodbye! [CHAPTER_COMPLETE]